The telecommunication system mainly includes wired telecommunication system and wireless telecommunication system. The subscriber equipment in the wired telecommunication systems is commonly identified with physical lines such as cables, and they are corresponding to each other; if the subscriber moves from one place to another, it needs the network operator to provide machine-moving service, and the subscriber can't enjoying service anytime and anywhere. While in the wireless network, because wireless access is free from the harassment of physical line, the wireless telecommunication system such as GSM, CDMA can provide roaming service inherently by using equipments such as VLR/HLR.
It is necessary to provide telecommunication service anytime and anywhere due to the increasing demand of communication, but if each time the subscriber moves to a new place, he has to use a new telephone number to access, the subscriber has to inform all of his relatives and friends of the new telephone number one by one, otherwise, if one wants to contact him, he obviously needs to get the new telephone number first. In contrast, the advantage brought by roaming service is self-evident: the subscriber can enjoy telecommunication service anywhere and anytime while only using one telephone number.
Currently, the next generation network architecture with soft switch as core control equipment still hasn't provided roaming function, but due to the inter-connectivity of broadband network, if the current location information of the subscriber can be located, it is possible for the subscriber in the next generation network architecture with soft switch as core control equipment to be able to enjoy roaming service.
In order to realize roaming, it needs to locate the position of the soft switch control device the subscriber currently located in. In the present invention, it is realized by the route server. As a network equipment, the route server is a device for providing route service, and providing interface for inquiring and modifying terminal location information.
China patent application No. 200310112905.X discloses a method and system for realizing call route by employing the route server (i.e. the route serving device in this article), in which the soft switch control device and the route server are networked in a layered manner, and the route server accomplishes the call route; when the subscriber route changes, the soft switch control device reports location update message, the subscriber route information is maintained through the steps of reporting and registering; when cross-domain calling, the calling soft switch equipment obtains the route of the soft switch control device the called located in, such as IP address, by initiating an inquiry request toward the route server; the subscriber in a certain domain can obtain location information, such as the domain anyone of the subscribers in the whole network located in, by accessing the route server.
It is an important problem waiting to be solved that how to realize subscriber's roaming service by employing the route function of the next generation network.